<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div.box {
      color: red;
    }
  </style>
</head>

<body>
  <div class="box">
    <h1>我是h1元素</h1>
    <p>
      我是p元素
      <span>哈哈哈</span>
      <strong>呵呵呵</strong>
    </p>
    <span>我是span元素</span>
  </div>
</body>

</html>